United Airlines customers got an unwelcome surprise this morning: Domestic departures were delayed more than a half hour because of what appears to be incorrect “dispatching information” in the airline’s computer systems.

According to tweets by customers flying out of different airports, pilots said incorrect flight plans were filed in United’s systems and had to be resolved.

The airline confirmed this.

In a statement to Fast Company, airline spokesperson Charles Hobart added “United began delaying flights at approximately 8 a.m. CT to ensure aircraft departed with proper dispatching information. We resumed departures at about 8:40 CT and are accommodating our customers to their destinations.”

Regardless of whether the incorrect dispatch information is the result of malicious hackers or technical errors, it is the second major IT issue United has faced in just over a month. On May 28, iPads used in the cockpit mysteriously began crashing, leading to flight delays. As part of a modernization effort, pilots and copilots at United and other major airline now access manuals and flight plans through tablets rather than paper.